With some of the small, hard-to-find parts you may have to look for, and buy, an entire part that the one thing you want is bolted to. I was looking for the same thing you were (because the PO had swapped to the pressure switches- I can't stand it, and wanted originality) and ended up buying an entire brake master cylinder. The good thing was the master cylinder itself was total crap, so I probably paid less for the entire thing than I would have for just the switch itself.
Had to do the same thing again to get the headlight mounting hardware for under the headlight- had to buy an entire front brake line and splitter that happened to have the necessary hardware still bolted on. I never would've found it otherwise.
